Well, if space is really a 5ft cube, I think I like space.
That's fine by me!
That means we've currently got the following. I've broken the Strangling vines up into 3 paragraphs to make it a bit more legible:
Strangle Vine
Small Plant
Hit Dice: 1d8+4 (8 hp)
Initiative: +0
Speed: 0 ft. (immobile)
Armor Class: 11 (+1 size), touch 11, flat-footed 11
Base Attack/Grapple: +0/-4
Attack: —
Full Attack: —
Space/Reach: 5 ft./0 ft.
Special Attacks: Strangling vines
Special Qualities: Blind, plant traits, tremorsense 20 ft.
Saves: Fort +3, Ref +1, Will +0
Abilities: Str 10, Dex 12, Con 13, Int --, Wis 8, Cha 3
Skills: —
Feats: Toughness (B)
Environment: Warm or temperate woods and swamps
Organization: Solitary; gallows (2-5) or copse (4-40)
Challenge Rating: 1/2
Treasure: 1/10th coins; 50% goods; 50% items
Alignment: Always neutral
Advancement: 2-3 HD (Medium); 4-8 HD (Large); 9-15 HD (Huge); 16-24 HD (Gargantuan); 25-36 HD (Colossal)
Level Adjustment: —
Combat
Strangling Vines (Ex): Any creature that enters the space of a strangle vine must succeed at a DC10 Reflex save or be seized by its vines. If they succeed, they must check again every round they remain within the plant's space.
Seized creatures are entangled, cannot move out of the space they where standing in when the vines seized them, and take 1d4 damage (plus Strength bonus, if any) per round from being "strangled". Any creature in a strangle vine's grasp cannot speak or cast spells with verbal components, because the vines wrap round their head and neck and try forcing themselves down their victim's throat.
A seized creature can escape by succeeding at a DC14 Strength check or a DC14 Escape Artist check. They can also break free by killing the strangle vine or cutting the vines that hold them; the vines are AC13 and have 4 hit points (8 hp for Medium strangle vines, 12 hp for Large, 18 hp for Huge, 24 hp for Gargantuan and 30 hp for Colossal). Severing the vines does half the vines' hit points in damage to the main plant. The DCs are Strength-based and include a +4 racial bonus on the Strength and Escape Artist checks.